dmsetup man page on aLinux

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       dmsetup - low level logical volume management

       dmsetup create device_name [-u uuid] [--notable] [table_file]
       dmsetup remove device_name
       dmsetup remove_all
       dmsetup suspend device_name
       dmsetup resume device_name
       dmsetup load device_name [table_file]
       dmsetup clear device_name
       dmsetup reload device_name [table_file]
       dmsetup rename device_name new_name
       dmsetup ls [--target target_type] [--exec command]
       dmsetup info [device_name]
       dmsetup info -c|-C|--columns [--noheadings] [-o name] [device_name]
       dmsetup deps [device_name]
       dmsetup status [--target target_type] [device_name]
       dmsetup table [--target target_type] [device_name]
       dmsetup wait device_name [event_nr]
       dmsetup mknodes [device_name]
       dmsetup targets
       dmsetup version

       devmap_name major minor
       devmap_name major:minor

       dmsetup	manages	 logical  devices  that	 use the device-mapper driver.
       Devices are created by loading a table that specifies a target for each
       sector (512 bytes) in the logical device.

       The first argument to dmsetup is a command.  The second argument is the
       logical device name or uuid.

       Invoking the command as devmap_name is equivalent to
       dmsetup info -c --noheadings -j major -m minor.

	      Display output in columns rather than as Field: Value lines.

       -j|--major major
	      Specify the major number.

       -m|--minor minor
	      Specify the minor number.

	      Suppress the headings line when using columnar output.

	      Tell the kernel not to supply the open reference count  for  the

	      When creating a device, don't load any table.

	      Specify which fields to display.	Only -o name is supported.

	      Set the table being loaded read-only.

	      Specify the uuid.

	      Produce additional output.

	      Display the library and kernel driver version.

       create device_name [-u uuid] [--notable] [table_file]
	      Creates  a  device  with	the given name.	 If table_file is sup‐
	      plied, the table is loaded and made live.	 Otherwise a table  is
	      read from standard input unless --notable is used.  The optional
	      uuid can be used in place of device_name in  subsequent  dmsetup
	      commands.	  If  successful  a device will appear as /dev/device-
	      mapper/<device-name>.  See below for information	on  the	 table

       deps   [device_name]
	      Outputs a list of (major, minor) pairs for devices referenced by
	      the live table for the specified device.

       info   [device_name]
	      Outputs some brief information about the device in the form:
		  Tables present: LIVE and/or INACTIVE
		  Open reference count
		  Last event sequence number (used by wait)
		  Major and minor device number
		  Number of targets in the live table

       ls     [--target target_type] [--exec command]
	      List device names.  Optionally only list devices	that  have  at
	      least  one  target  of the specified type.  Optionally execute a
	      command for each device.	The device name	 is  appended  to  the
	      supplied command.

	      device_name [table_file]
	      Loads  table_file	 into the inactive table slot for device_name.
	      If table_file is not  supplied,  reads  a	 table	from  standard

       remove device_name
	      Removes  a  device.  It will no longer be visible to dmsetup and
	      will be deleted when its open_count is zero.

	      Attempts to remove all device definitions i.e. reset the driver.
	      Use with care!

       rename device_name new_name
	      Renames a device.

       resume device_name
	      Un-suspends  a device.  If an inactive table has been loaded, it
	      becomes live.  Postponed I/O then gets re-queued for processing.

       status [--target target_type] [device_name]
	      Outputs status information for each  of  the  device's  targets.
	      With --target, only information relating to the specified target
	      type is displayed.

	      Suspends a device.  Any I/O that has already been mapped by  the
	      device  but  has not yet completed will be flushed.  Any further
	      I/O to that device will be postponed for as long as  the	device
	      is suspended.

       table  [--target target_type] [device_name]
	      Outputs the current table for the device in a format that can be
	      fed back in using the create or load commands.   With  --target,
	      only  information	 relating to the specified target type is dis‐

	      Displays the names and versions of the currently-loaded targets.

	      Outputs version information.

       wait   device_name [event_nr]
	      Sleeps until the event counter for device_name exceeds event_nr.
	      Use -v to see the event number returned.	To wait until the next
	      event is triggered, use info to find the last event number.

       Each line of the table specifies a single target and is of the form:
	   logical_start_sector num_sectors target_type target_args

       There are currently three simple target types available	together  with
       more complex optional ones that implement snapshots and mirrors.

       linear destination_device start_sector
	      The traditional linear mapping.

	      num_stripes chunk_size [destination start_sector]+
	      Creates a striped area.
	      e.g.  striped  2	32  /dev/hda1 0 /dev/hdb1 0 will map the first
	      chunk (16k) as follows:
		  LV chunk 1 -> hda1, chunk 1
		  LV chunk 2 -> hdb1, chunk 1
		  LV chunk 3 -> hda1, chunk 2
		  LV chunk 4 -> hdb1, chunk 2

	      Errors any I/O that goes to this area.  Useful  for  testing  or
	      for creating devices with holes in them.

       # A table to join two disks together
       0 1028160 linear /dev/hda 0
       1028160 3903762 linear /dev/hdb 0

       # A table to stripe across the two disks,
       # and add the spare space from
       # hdb to the back of the volume

       0 2056320 striped 2 32 /dev/hda 0 /dev/hdb 0
       2056320 2875602 linear /dev/hdb 1028160

       Original version: Joe Thornber (

       Device-mapper resource page:

Linux				  Sep 17 2003			    DMSETUP(8)

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